The typical known art of surgically resurfacing the natural patella, when necessary to accept an artificial patella prosthesis, requires the patella to be everted and held in a position allowing the surgeon to have access to the articulating surface which normally articulates within the intercondylar notch between the femoral condyles.
The natural patella is first measured, establishing its exact thickness, after which the surgeon resects the appropriate thickness of the posterior portion of the natural patella, and then prepares the surface to receive the artificial patella prosthesis. A patella trial replicating the actual implant to be installed is placed upon the prepared patella surface to confirm proper fit and thickness of the patella construct that establishes proper ligamentus tension for optimum stability and range of motion whereupon, a bonding agent (e.g., bone cement) is prepared. In the typical known handling of the bone cement, there is an exact science of measured polymer (e.g., powder) and monomer (e.g., liquid) packaged sterile in their individual respective states delivered into a sterile field placed into and enclosed in a sterile container whereupon measured vacuum force is applied and a measured time of thorough mixing is conducted. The properties are handled under strict scrutiny and respectful disciplines. When the vacuum is released, the top of the sterile container can be removed, giving access to the bone cement, whereupon it is examined to confirm that it is in the proper state to be applied. Precautions are generally taken to create the bone cement and bring it into a proper stable useable product, whereby it can be applied in order to successfully bond the aforementioned surfaces. At this juncture, a patella clamp is applied to the patella construct (which consists of the surgically resurfaced posterior aspect of natural patella prepared to receive an artificial patella replacement paired with the bonding agent bone cement). However, past methods and devices for applying the pressure have not been controlled and have resulted in the application of an arbitrary and unknown pressure upon the patella construct until the bone cement is fully cured. As such, less than satisfactory results can occur.
Measured pressure upon the patella construct is a paramount consideration to the mechanical properties, scientific quantitation and increased long-term success of the bonding integrity of the bone cement. Heretofore, no patella clamp has existed for general surgical use which takes into account all the parameters and dynamics taking place within the patella construct as it relates to all surfaces involved and the scientific and mechanical properties of the bonding agent bone cement during installation, as well as, the potential of excessive unknown pressure upon the host patella creating micro fractures. Further, past patella clamps have not addressed the need for contact surface adapters and components that protect the user during and after preparation and operation while providing a disposable component facilitating accurate relative sizing and post-operative cleaning.
In various aspects, the present invention enables the medical professional (e.g., a surgeon) to accurately apply positive linear directional control and known pressure upon the patella construct throughout the process to the cure state of the bone cement, while protecting the professional during and after preparation and operation while providing a disposable component facilitating accurate relative sizing and post-operative cleaning. After the initial proper pressure is established upon the patella construct, certain variables can come into play affecting the applied pressure. In various aspects, the present invention allows the attending medical professional(s) to stay informed as to pressure changes, giving the medical professional(s) the capability to re-establish correct pressure by known positive control.
Aspects and embodiments of the current inventive device receive the everted patella in its prepared form whereupon the anterior portion of the natural patella is placed upon a spiked platform of a bottom plate associated with the various embodiments of the device. The adapter and components according to embodiments of the present invention cover the spiked platform before and after use while further providing a disposable component facilitating accurate relative sizing and post-operative cleaning. Upon the patella being held in place, the surgeon or other medical professional takes hold of the knob of the knob assembly of the present device, holding it firmly in one hand. With the other hand, the medical professional depresses a quick release button of one embodiment of the present device, freeing the adjustment rod thereupon. As the medical professional pushes downward atop the knob in this embodiment, the indicating assembly of the present device translates downward in a controlled linear direction as its slide ring houses and translates upon the keyed guide rod acting as an established vertical stable construct. When the patella bushing or adapter device of the present invention makes contact with the artificial patella of the patella construct, the medical professional can apply controlled pressure, and an indicating assembly measures the pressure being applied and an assembly contained calibrated indicator gives visual knowledge and reference as to the precise amount of measured applied pressure being applied.
In alternative embodiments, a medical professional secures an appropriately sized and configured insert into the device, ensures that the everted patella is appropriately situated in the receiving area of the device, and adjusts a knob assembly to a desired level associated with a measured pressure.
Upon the surgeon creating the specific required and known applied pressure, the clockwise turning motion upon the assembly knob can be terminated. At this time, the bonding agent within the patella construct will squeegee out; the bottom platform spikes will depress into the anterior patella and the bushing (e.g., a rubber bushing or of other material and design) in the stem of the clamp indicating assembly can settle in. It will be appreciated that the above processes can take effect within seconds and the amount of applied pressure can thereafter decrease.
Thereupon, the present inventive device indicator visually informs the medical professional(s) of the potential adverse change in pressure and this calibrated reference gives the necessary information to correct and re-establish proper pressure. In the event of change from optimum applied pressure, the medical professional can create additional needed known applied pressure by again turning the assembly knob to re-establish the precise prescribed pressure to be upon the patella construct. The present invention thus, in part, enables the medical professional to create and maintain measured applied pressure upon the patella construct until the bone cement is fully cured. Upon the professional confirming the bone cement is fully cured, the present device can be removed by turning the knob in the opposite direction from the direction used to apply pressure, thereby relieving pressure off the indicating device. An adapter device secured to the clamp can then be discarded and the clamp device thoroughly cleaned, particularly around areas close to the operative procedure so as to be appropriately prepared for further use.
Among other things, the present invention substantially improves procedures in the installation of an artificial patella prosthetic replacement in total knee arthroplasty and is also introductory to additional improvements within a system of surgical instrumentation.